[Haskell-cafe] What is the state of the art in testing code generation?

[João Cristóvão]

I'm not sure if this is related and/or applicable, but you didn't seem
to mention:

https://hackage.haskell.org/package/hssqlppp

Its a SQL parser/checker.

Cheers,
João

2014-07-11 21:03 GMT+01:00 Alexander Solla <alex.solla at gmail.com>:
> On Fri, Jul 11, 2014 at 10:58 AM, Tom Ellis
> <tom-lists-haskell-cafe-2013 at jaguarpaw.co.uk> wrote:
>>
>> I am implementing an EDSL that compiles to SQL and I am wondering what is
>> the state of the art in testing code generation.
>>
>> All the Haskell libraries I could find that deal with SQL generation are
>> tested by implementing multiple one-off adhoc queries and checking that
>> when
>> either compiled to SQL or run against a database they give the expected,
>> prespecified result.
>
>
>
>>
>> Is this the best we can do in Haskell?  Certainly it seems hard to use a
>>
>> QuickCheck/SmallCheck approach for this purpose.  Is there any way this
>> kind
>> of testing can be automated or made more robust?
>
>
> Personally, I would test this in the same way I'd test a compiler: as purely
> as possible.  You have an EDSL, and possibly an AST for it, and finally a
> target language.  Figure out if any one of the layers is particularly
> "shallow" (and therefore "easy" to validate by inspection).  Use the shallow
> layer to validate the other two.
>
> The trouble with this approach is that you'll need to find a way to
> "interpret" raw SQL statements, since different can be equivalent modulo
> ordering of fields, subqueries, conditions, etc.  So, as an architectural
> point, I would make the AST -> SQL layer the "easy" one to validate.  Then,
> you can check that your EDSL -> AST layer produces the expected trees.  You
> can even use QuickCheck for this validation.
>
> Otherwise, you will have to do it impurely, like the other packages do.
>
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